Ever since reading Richard Dawkins' book 'The Blind Watchmaker' I'd wanted to try my hand at some evolutionary programming. The idea is to model natural selection inside the computer by generating procedural creatures and allowing them to vary and improve over time without user intervention.
The code to build and rig the robots was written in Python, as was the code to run the rigid body simulation, using the Open Dynamics Engine to drive the sim. I wrote an importer for Side Effects' Houdini to read in my robot simulations so I could render them out as pictures.
If you enjoyed the Tunzelbots, here are some other videos you might like:
Karl Sims - Evolved Virtual Creatures, Evolution Simulation, 1994
Nick Cheney, Rob MacCurdy, Jeff Clune, Hod Lipson - Evolving Soft Robots with Multiple Materials
Thomas Geijtenbeek, Michiel van de Panne, Frank van der Stappen - Flexible Muscle-Based Locomotion for Bipedal Creatures
And there's a bit about Richard Dawkins' Biomorphs here: